hydrophobic 0.22 um syringe filter Corning Red PTFE (Hydrophilic) Syringe Filters, 0.22 µm, 13 mm (100 The PerkinElmer Red PTFE (Hydrophilic) Syringe Filters, 0.22 µm, 13 mm (100/pack) have broad chemical compatibility and high pH resistance and are optically clear when wet with water.